This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application No(s). 2002-122846 filed in JAPAN on Apr. 24, 2002, which is(are) herein incorporated by reference.
1. Field of the Invention
The present invention relates to expandable/contractible type portable printers.
2. Description of the Related Art
Ink jet printers in general are constructed to be capable of printing on recording sheets of A4 size or larger and hence are relatively bulky and heavy. Such a printer is inconvenient for the user to carry, and frequently occupies a large space when not in use. In attempt to overcome such inconveniences, a portable image output device capable of expanding/contracting the printing area in the primary scanning direction has been proposed in Japan Patent Laid Open Hei No. 10-230662 for example.
This image output device has two expandable/contractible rods forming a guide shaft for guiding a whole device body and a carriage in the primary scanning direction. The expandable/contractible rods each comprise a larger tubular shaft, and a smaller shaft telescopically movable in the larger shaft. The image output device is so constructed that the guide shaft supports a guide shaft bearing of the carriage in a non-contact state by utilizing magnetic and/or electrostatic repulsion.
The image output device employing such an expandable/contractible guide shaft has the drawback that when the guide shaft is expanded to the maximum, the overlapping portion between the larger shaft and the smaller shaft becomes so small that a sufficient strength for use cannot be ensured, resulting in the guide shaft likely to collapse.
Further, since the carriage is supported in a non-contact state above the guide shaft so as to avoid the influence of a stepped portion defined on the expandable/contractible guide shaft, the carriage is greatly influenced when the whole device is given an external shock or the carriage receives vibration or the like from the carriage driving source, and as a result, vibration of the carriage is generated having an amplitude corresponding to the gap between the carriage and the guide shaft about the axis of the guide shaft, thereby deteriorating the quality of printed images.
It is an object of the present invention to provide an expandable/contractible type portable printer which is capable of establishing a large amount of expansion/contraction while ensuring a high coupling strength between an enclosure and opposite outer jackets when the printer is in use.
According to the present invention, there is provided an expandable/contractible type portable printer comprising:
an expandable/contractible casing including an enclosure and opposite outer jackets expandably and contractibly mounted at opposite sides of the enclosure;
a printing unit disposed in the casing for printing on a recording sheet by jetting ink onto the recording sheet from a printing head mounted on a carriage which is reciprocatively movable in a primary scanning direction; and
a sheet feed unit disposed in the casing for feeding the recording sheet in a secondary scanning direction,
the opposite outer jackets being coupled to the enclosure by means of a rack-and-pinion mechanism so as to be expandable and contractible with respect to the enclosure evenly in opposite lateral directions.
It is desired that the expandable/contractible type portable printer have a carriage guide member of a stepless structure for reducing the influence of vibration from a carriage driving motor or the like.
In the printer of this construction, the opposite outer jackets are coupled to the enclosure by means of the rack-and-pinion mechanism so as to be expandable and contractible with respect to the enclosure evenly in the opposite lateral directions. This feature facilitates the operation of expanding and contracting the casing thereby to improve the ease of use of the printer and ensures a high strength of coupling between the enclosure and the opposite outer jackets when the printer is in use.
The rack-and-pinion mechanism employed in the printer allows an increased amount of expansion/contraction of the casing to be established, thereby enabling printing on large-size recording sheets when the printer is in use and allowing the printer to be contracted into a compact size when the printer is not in use.
The foregoing and other objects, features and attendant advantages of the present invention will become apparent from the reading of the following detailed description in conjunction with the accompanying drawings.